Vertical fuse structures

ABSTRACT

Semiconductor devices and methods are provided in which vertical fuse devices are integrally formed with FINFET (Fin Field Effect Transistor) devices, wherein the vertical fuse devices are formed as part of a process flow for fabricating the FINFET devices. For example, a semiconductor device comprises first and second vertical semiconductor fins, a vertical fuse device, and a FINFET device. The vertical fuse device comprises a metal fuse element formed over a portion of the first vertical semiconductor fin, and the FINFET device comprises a metal gate electrode formed over a portion of the second vertical semiconductor fin. The metal fuse element and the metal gate electrode are concurrently formed as part of a replacement metal gate process flow.

TECHNICAL FIELD

This disclosure relates generally to semiconductor fabricationtechniques and, in particular, to structures and methods for fabricatingelectrical fuse structures.

BACKGROUND

A fuse is an electrical device which has a low resistance conductivepath that is designed to be broken when an electrical current throughthe low resistance conductive path exceeds a specified limit. Electricalfuses are utilized in semiconductor integrated circuits for variousapplications including, for example, enabling redundant circuitry,programming one-time programmable read-only memory (PROM), configuringprogrammable logic devices (PLDs), trimming elements in analog trimmingcircuitry, implementing chip identification circuitry, etc. Thedimensions of integrated fuse devices in semiconductor circuitry islimited by the allowable photolithographic minimal dimensions. Moreover,the fabrication of integrated fuse devices using conventional CMOStechnologies can require multiple deposition and lithographic maskingsteps, which is time consuming and expensive. In this regard, the amountand complexity of additional processing steps that are incorporated aspart of a semiconductor process flow to fabricate integrated fusedevices should be minimized to reduce the fabrication costs andprocessing time for constructing semiconductor chips with integratedfuse devices. Furthermore, the footprint area occupied by integratedfuse devices should be minimized, as well as the power consumption ofintegrated fuse devices.

SUMMARY

Embodiments of the invention include semiconductor devices havingvertical fuse devices that are integrated with FINFET (Fin Field EffectTransistor) devices, as well as methods for integrally forming verticalfuse devices as part of a process flow for fabricating FINFET devices.

For example, one embodiment of the invention includes a method forforming a semiconductor device. The method comprises forming a pluralityof vertical semiconductor fins on a semiconductor substrate, wherein theplurality of vertical semiconductor fins include a first verticalsemiconductor fin and a second vertical semiconductor fin; forming avertical fuse device having a first dummy gate structure formed over aportion of the first vertical semiconductor fin; forming a FINFET devicehaving a second dummy gate structure formed over a portion of the secondvertical semiconductor fin; and performing a RMG (replacement metalgate) process to remove the first and second dummy gate structures, andto replace the first dummy gate structure with a metal fuse element forthe vertical fuse device and replace the second dummy gate structurewith a metal gate electrode for the FINFET device.

Another embodiment of the invention includes a semiconductor device. Thesemiconductor device comprises a plurality of vertical semiconductorfins formed on a semiconductor substrate, wherein the plurality ofvertical semiconductor fins comprises a first vertical semiconductor finand a second vertical semiconductor fin. The semiconductor devicefurther comprises a vertical fuse device and a FINFET device. Thevertical fuse device comprises a metal fuse element formed over aportion of the first vertical semiconductor fin, wherein the metal fuseelement comprises a first conformal metal layer formed on the portion ofthe first vertical semiconductor fin, and a first metal electrode layerformed on the first conformal metal layer. The FINFET device comprises ametal gate electrode formed over a portion of the second verticalsemiconductor fin, wherein the metal gate electrode comprises a high-kmetal gate stack structure conformally formed on the portion of thesecond vertical semiconductor fin, and a second metal electrode layerformed on the high-k metal gate stack structure. The high-k metal gatestack structure comprises a conformal layer of dielectric materialformed on the portion of the second vertical semiconductor fin and asecond conformal metal layer formed on the conformal layer of dielectricmaterial. The first conformal metal layer and the second conformal metallayer are patterned from a same conformal layer of metallic material,and the first metal electrode layer and the second metal electrode layerare patterned from a same layer of metallic material.

Other embodiments will be described in the following detaileddescription of embodiments, which is to be read in conjunction with theaccompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A, 1B, and 1C are schematic views of a semiconductor devicehaving vertical fuse devices that are integrated with FINFET devices,according to an embodiment of the invention.

FIG. 2 schematically illustrates a method for programming a verticalfuse device of the semiconductor device shown in FIG. 1A, according toan embodiment of the invention.

FIGS. 3A/3B/3C through FIGS. 13A/13B/13C schematically illustrate amethod for fabricating the semiconductor device of FIGS. 1A/1B/1C,according to an embodiment of the invention, wherein:

FIGS. 3A/3B/3C are cross-sectional views of the semiconductor device atan intermediate stage of fabrication in which vertical fuse devices withdummy gate structures are formed in a first device region, and FINFETdevices with dummy gate structures are formed in second device region;

FIGS. 4A/4B/4C are cross-sectional views of the semiconductor structureof FIGS. 3A/3B/3C after removing the dummy gate structures of thevertical fuse devices and FINFET devices to form recessed regionsbetween insulating sidewall spacers;

FIGS. 5A/5B/5C are cross-sectional views of the semiconductor structureof FIGS. 4A/4B/4C after depositing a conformal layer of gate dielectricmaterial and depositing a conformal protective capping layer over theconformal layer of gate dielectric material;

FIGS. 6A/6B/6C are cross-sectional views of the semiconductor structureof FIGS. 5A/5B/5C after removing the conformal layer of gate dielectricmaterial and the protective capping layer in the first device;

FIGS. 7A/7B/7C are cross-sectional views of the semiconductor structureof FIGS. 6A/6B/6C after removing the protective capping layer in thesecond device region and depositing a conformal layer of work functionmetal over the first and second device regions; FIGS. 8A/8B/8C arecross-sectional views of the semiconductor structure of FIGS. 7A/7B/7Cafter depositing an organic planarizing layer to fill the recessedregions between the insulating sidewall spacers;

FIGS. 9A/9B/9C are cross-sectional views of the semiconductor structureof FIGS. 8A/8B/8C after etching the organic planarizing layer to atarget level within the recessed regions between the insulating sidewallspacers;

FIGS. 10A/10B/10C are cross-sectional views of the semiconductorstructure of FIGS. 9A/9B/9C after etching away exposed portions of theconformal layer of work function metal in the first and second deviceregions and etching away exposed portions of the conformal layer of gatedielectric material in the second device region;

FIGS. 11A/11B/11C are cross-sectional views of the semiconductorstructure of FIGS. 10A/10B/10C after stripping away remaining portionsof the organic planarizing layer and depositing a layer of metallicmaterial to fill the recessed regions between the insulating sidewallspacers with the metallic material;

FIGS. 12A/12B/12C are cross-sectional views of the semiconductorstructure of FIGS. 11A/11B/11C after etching the layer of metallicmaterial down to the target level within the recessed regions betweenthe insulating sidewall spacers to form a metal gate electrode; and

FIGS. 13A/13B/13C are cross-sectional views of the semiconductorstructure of FIGS. 12A/12B/12C after forming dielectric capping layersto cover the metal gate electrodes.

DETAILED DESCRIPTION

Embodiments of the invention will now be described in further detailwith regard to semiconductor devices having vertical fuse devices thatare integrated with FINFET devices, as well as methods for integrallyforming vertical fuse devices as part of a FEOL (front-end-of-line)process flow for fabricating FINFET devices. As explained in furtherdetail below, semiconductor fabrication techniques according toembodiments of the invention enable vertical fuse structures to bereadily fabricated using CMOS (complementary metal oxide semiconductor)process modules in a FEOL process flow to construct FINFET deviceswithout the need for additional processes steps or processing time toconstruct the vertical fuse devices. The exemplary semiconductor processflows described herein allow integration of vertical fuse devices withFINFET devices for technology nodes of 7 nm and beyond.

It is to be understood that the various layers, structures, and regionsshown in the accompanying drawings are schematic illustrations that arenot drawn to scale. In addition, for ease of explanation, one or morelayers, structures, and regions of a type commonly used to formsemiconductor devices or structures may not be explicitly shown in agiven drawing. This does not imply that any layers, structures, andregions not explicitly shown are omitted from the actual semiconductorstructures.

Furthermore, it is to be understood that the embodiments discussedherein are not limited to the particular materials, features, andprocessing steps shown and described herein. In particular, with respectto semiconductor processing steps, it is to be emphasized that thedescriptions provided herein are not intended to encompass all of theprocessing steps that may be required to form a functional semiconductorintegrated circuit device. Rather, certain processing steps that arecommonly used in forming semiconductor devices, such as, for example,wet cleaning and annealing steps, are purposefully not described hereinfor economy of description.

Moreover, the same or similar reference numbers are used throughout thedrawings to denote the same or similar features, elements, orstructures, and thus, a detailed explanation of the same or similarfeatures, elements, or structures will not be repeated for each of thedrawings. It is to be understood that the terms “about” or“substantially” as used herein with regard to thicknesses, widths,percentages, ranges, etc., are meant to denote being close orapproximate to, but not exactly. For example, the term “about” or“substantially” as used herein implies that a small margin of error ispresent, such as 1% or less than the stated amount.

FIGS. 1A, 1B and 1B are schematic views of a semiconductor device 100having vertical fuse devices that are integrated with FINFET devices,according to an embodiment of the invention. FIG. 1A is a schematic sideview of the semiconductor device 100, FIG. 1B is a schematiccross-sectional view of the semiconductor device 100 taken along line1B-1B in FIG. 1A, and FIG. 1C is a schematic cross-sectional view of thesemiconductor device 100 taken along line 1C-1C in FIG. 1A. Morespecifically, FIG. 1A is a schematic side view of the semiconductordevice 100 in a X-Z plane, and FIGS. 1B and 1C are cross-sectional viewsof the semiconductor device 100 in a Y-Z plane, as indicated by therespective XYZ Cartesian coordinates shown in FIGS. 1A, 1B, and 1C. Itis to be understood that the term “vertical” or “vertical direction” asused herein denotes a Z-direction of the Cartesian coordinates shown inthe drawings, and the term “horizontal” or “horizontal direction” asused herein denotes an X-direction and/or Y-direction of the Cartesiancoordinates shown in the drawings.

As collectively shown in FIGS. 1A/1B/1C, the semiconductor device 100comprises a substrate 110/115 which includes a bulk substrate layer 110and an insulating layer 115 (e.g., a buried oxide layer of an SOIsubstrate), a plurality of vertical fuse devices F1 and F2 formed in afirst region R1 (or vertical fuse device region) of the semiconductordevice 100, and a FINFET device T1 formed in a second device region R2(or FINFET device region) of the semiconductor device 100. Each verticalfuse device F1 and F2 comprises a vertical semiconductor fin 120 (whichextends along the substrate 110/115 in an X-direction as shown),insulating sidewall spacers 140, an insulating capping layer 145, and ametallic fuse element 160. The insulating sidewall spacers 140 andcapping layer 145 serve to encapsulate and insulate the metallic fuseelement 160 from surrounding structures. The FINFET device T1 comprisesa vertical semiconductor fin 122 (which extends along the substrate110/115 in an X direction as shown), insulating sidewall spacers 140, aninsulting capping layer 145, and a metal gate electrode 150. Thevertical semiconductor fin 122 provides a vertical channel for theFINFET device T1 along a portion of the vertical semiconductor fin 122which is encapsulated/surrounded by the metal gate electrode 150.

In one embodiment of the invention, the metal gate electrode 150 of theFINFET device T1 and the metallic fuse elements 160 of the vertical fusedevices F1 and F2 are concurrently formed as part of a RMG (replacementmetal gate) process flow, which will be discussed in further detailbelow. As shown in FIGS. 1A and 1C, the metal gate electrode 150 of theFINFET device T1 comprises a thin conformal gate dielectric layer 152(which conformally covers a segment of the vertical semiconductor fin122 that serves as the vertical channel for the FINFET device T1), athin conformal work function metal (WFM) layer 154 that is formed overthe conformal gate dielectric layer 152, and a metal electrode layer156. In one embodiment of the invention, the conformal gate dielectriclayer 152 and the conformal WFM layer 154 comprise a high-k metal gatestack structure 152/154.

Moreover, as shown in FIGS. 1A and 1B, the metallic fuse elements 160 ofthe vertical fuse devices F1 and F2 each comprise layers of the samemetallic materials 154 and 156 used to form the conformal WFM layer 154and the metal electrode layer 156 of the FINFET device T1. The metallicfuse elements 160 are formed as part of a RMG process flow that is usedto form metal gate electrodes (e.g., metal gate electrode 150) of theFINFET devices (e.g., FINFET device T1) in the second device region R2of the semiconductor device 100. However, while the conformal gatedielectric layer 152 is deposited over both device regions R1 and R2 aspart of the RMG process flow, the portion of the conformal gatedielectric layer 152 in the vertical fuse device region R1 is removedprior to depositing the layers of metallic material used to form theconformal WFM layer 154 and the metal electrode layer 156 in the deviceregions R1 and R2.

As further depicted in FIGS. 1A, 1B, and 1C, the vertical fuse devicesF1/F2 and the FINFET device T1 are encapsulated in a layer of insulatingmaterial 130. In one embodiment of the invention, the layer ofinsulating material 130 comprises a PMD (pre-metal dielectric) layer ofa MOL (middle of the line) layer of the semiconductor device 100. Thesemiconductor device 100 further comprise a plurality of verticalcontacts (e.g., contacts 200, 202, 210 and 212) formed in the cappinglayers 145 of the vertical devices F1, F2, and T1, and in the layer ofinsulating material 130. The contacts 200, 202, 210 and 212 may beconsidered MOL device contacts that are formed as part of the MOL layerof the semiconductor device 100 to provide vertical contacts to thevertical devices F1, F2 and T1. Each MOL device contact may comprises aliner/barrier layer and a conductive via, as is known in the art.

The fuse contact terminals 200 are formed in openings that are patternedin the capping layers 145 of the vertical fuse devices F1 and F2 toprovide contacts to the metallic fuse elements 160 of the vertical fusedevices F1 and F2. The fuse contact terminal 202 is formed in an openingthat is patterned in the layer of insulating material 130 to makecontact with a portion of the vertical semiconductor fin 120 between theadjacent vertical fuse devices F1 and F2. In this structuralconfiguration, the vertical semiconductor fin 120 in the vertical fusedevice region R1 serves as one segment of a conducting path between thefirst fuse contact terminal 200 (e.g., anode) and the second fusecontact terminal 202 (e.g., cathode) of the vertical fuse devices F1 andF2, while each metallic fuse element 160 serves as another segment ofthe conducting path between the first and second fuse contact terminals200 and 202 of the vertical fuse devices F1 and F2. In the exampleembodiment shown in FIG. 1A, the adjacent vertical fuse devices F1 andF2 commonly share the second fuse contact terminal 202.

The gate contact 212 (FIG. 1C) is formed in an opening that is patternedin the capping layer 145 of the FINFET device T1 to provide a contact tothe metal gate electrode 150 of the FINFET device T1. The source/draincontacts 210 are formed openings that are patterned in the layer ofinsulating material 130 to make contact with portions of the verticalsemiconductor fin 120 which serve as source/drain regions of the FINFETdevice T1.

It is to be understood that the vertical semiconductor fins 120 and 122are generically depicted through the drawings, but can be formed ofdifferent materials using various fabrication methods. For example, thevertical semiconductor fins 120 and 122 can be formed byetching/patterning an active silicon layer that is formed on top of theinsulating layer 115 (e.g., an SOI layer of an SOI substrate). Inanother embodiment, the vertical semiconductor fins 120 and 122 can beformed by patterning an upper surface of a bulk semiconductor substrate.In yet another embodiment, the vertical semiconductor fins 120 and 122may be formed by depositing a layer of insulating material on top of asemiconductor substrate, patterning the layer of insulating material toform a pattern of trenches in the insulating material which correspondsto the pattern of vertical semiconductor fins to be fabricated, and thenperforming a bottom-up epitaxial growth process to grow epitaxialsemiconductor material within the trenches to form the verticalsemiconductor fins 120 and 122. In one example embodiment of theinvention, the vertical semiconductor fins 120 and 122 are formed with avertical height in a range of about 25 nm to about 30 nm.

Depending on the target application, the vertical semiconductor fins 120and 122 may be formed of silicon material, SiGe material, epitaxiallygrown semiconductor material, compound semiconductor materials (e.g.,III-V material), etc. Further, to increase the conductivity of thesemiconductor material of the vertical semiconductor fin 120 for thevertical fuse devices F1 and F2, the vertical semiconductor fin 120 inthe device region R1 can be doped with, e.g., n-type dopants or p-typedopants, using known ion implantations methods followed by annealing.

Further, the vertical semiconductor fin 122 in the FINFET device regionR2 may comprise epitaxial source/drain regions (e.g., drain region (D)and source region (S) as depicted in FIG. 1A) that are epitaxially grownon the portions of the vertical semiconductor fin 122 that extend fromthe insulating sidewall spacers 140 of the metal gate electrode 150,which are contacted by the source/drain contacts 210. Moreover, silicidelayers can be formed on areas of the vertical semiconductor fins 120 and122 to provide ohmic contacts between the vertical semiconductor fins120 and 122 and the vertical contacts 202 and 210. It is to beunderstood that the term “source/drain region” as used herein means thata given source/drain region can be either a source region or a drainregion, depending on the application.

In one embodiment of the invention, the programming (or “burning”) of avertical fuse device (e.g., vertical fuse device F1 or F2) is achievedby breaking the conductive path between the first fuse contact terminal200 and the second fuse contact terminal 202 of a given vertical fusedevice by the application of a high DC voltage applied to the verticalfuse device across the first and second fuse contact terminals 200 and202. For example, FIG. 2 schematically illustrates a method forprogramming a vertical fuse device of the semiconductor device shown inFIG. 1A, according to an embodiment of the invention. In particular,FIG. 2 illustrates a method of programming the vertical fuse device F1by applying a DC programming voltage VP to the first and second fusecontact terminals 200 and 202 to generate a high current density in themetallic fuse element 160. The high current density in the metallic fuseelement 160 causes a significant increase in the heat density of themetallic material of the thin WFM layer 154 at the interface between thevertical semiconductor fin 120 and the metal electrode layer 156. Theincreased current density, and thus heat density, causes the metallicmaterial of the thin WFM layer 154 to melt and/or vaporize, and generatea void 300 (or high resistance region). This effectively results inbreaking the low-resistance conductive path (through the metallic fuseelement 160 and the vertical semiconductor fin 120) between the firstand second fuse contact terminals 200 and 202. On the other hand, when anormal operating voltage is applied to the first and second fuse contactterminals 200 and 202, current will flow through the metallic fuseelement 160 and the vertical semiconductor fin 120 between the first andsecond fuse contact terminals 200 and 202, without causing the verticalfuse device F1 to blow (e.g., without melting/vaporing the thin WFMlayer 154).

Methods for fabricating the semiconductor device 100 shown in FIGS.1A/1B/1C will now be discussed in further detail with reference to FIGS.3A/3B/3C through FIGS. 13A/13B/13C, which schematically illustrate thesemiconductor device 100 of FIGS. 1A/1B/C at various stages offabrication. To begin, FIGS. 3A/3B/3C are cross-sectional views of thesemiconductor device 100 at an intermediate stage of fabrication inwhich the vertical fuse devices F1 and F2 and FINFET device T1 areformed with dummy gate structures 170. FIG. 3B is a schematiccross-sectional view of the semiconductor structure of FIG. 3A takenalong line 3B-3B in FIG. 3A, and FIG. 3C is a schematic cross-sectionalview of the semiconductor structure of FIG. 3A taken along line 3C-3C inFIG. 3A. The semiconductor structure shown in FIGS. 3A/3B/3C can befabricated using known materials and known semiconductor fabricationtechniques.

For example, as noted above, in one embodiment, the substrate 110/115comprises a SOI substrate, wherein the base substrate 210 is formed ofsilicon, or other types of semiconductor substrate materials that arecommonly used in bulk semiconductor fabrication processes such asgermanium, silicon-germanium alloy, silicon carbide, silicon-germaniumcarbide alloy, or compound semiconductor materials (e.g. III-V andII-VI). Non-limiting examples of compound semiconductor materialsinclude gallium arsenide, indium arsenide, and indium phosphide. Theinsulating layer 115 (e.g., oxide layer) is disposed between the basesemiconductor substrate 110 and an active semiconductor layer (e.g.,active silicon layer), wherein the active semiconductor layer ispatterned using known methods to fabricate the semiconductor finstructures 120 and 122.

Moreover, epitaxial source/drain regions can be epitaxially grown onexposed portions of the semiconductor fin structure 122 using knownmethods, such as such as CVD (chemical vapor deposition), MOCVD(metal-organic CVD), LPCVD (Low Pressure CVD), MBE (molecular beamepitaxy), VPE (vapor-phase epitaxy), or other known epitaxial growthtechniques which are suitable for the given process flow. The type ofepitaxial semiconductor material that is used to form source/drainregions on the exposed portions of the vertical semiconductor fin 122will vary depending on various factors including, but are not limitedto, the type of material of the vertical semiconductor fin 122, thedevice type (e.g., n-type or p-type) of the FINFET device T1, etc.Moreover, the source/drain regions S/D can be doped using standarddoping techniques. For example, the doping of the source/drain regionscan be performed in-situ during the epitaxial growth of the source/drainregions, or ex-situ by ion implantation. For example, the source/drainregions can be doped with Group III elements (for p-type FINFET devices)or Group V elements (for n-type FINFET devices). Typical dopants includeBoron, Arsenic, Phosphorus, Gallium, Antimony, etc. For example, boronis a p-type dopant, whereas Phosphorus is an n-type dopant.

As shown in FIGS. 3B and 3C, each dummy gate structure 170 comprises adummy gate oxide layer 172 which conformally covers the verticalsemiconductor fins 120 and 122, and a dummy poly gate layer 174 which,in one embodiment, comprises polysilicon. The dummy gate structures 170are formed using known techniques. For example, a thin conformal layerof silicon oxide is formed over the vertical semiconductor fins 120 and122, followed by the deposition of a layer of polysilicon over thevertical semiconductor fins 120 and 122. The silicon oxide andpolysilicon layers are then patterned using known techniques to form thedummy gate structures 170 over target regions of the verticalsemiconductor fins 120 and 122 where the vertical fuse and FINFETdevices are to be formed in the device regions R1 and R2.

After forming the dummy gate structures 170, the insulating sidewallspacers 40 are formed by depositing a layer of dielectric material, suchas silicon nitride (SiN), to encapsulate the dummy gate structures 170,followed by patterning the layer of dielectric material using knowntechniques. The layer of insulating material 130 (e.g., PMD layer 130)is formed by depositing a layer of dielectric material over the surfaceof the semiconductor device, and then planarizing the dielectricmaterial down to the upper surface of the dummy gate structures 170. ThePMD layer 130 may be formed with any suitable insulating/dielectricmaterials such as, for example, silicon oxide, silicon nitride,hydrogenated silicon carbon oxide, silicon based low-k dielectrics,porous dielectrics, or organic dielectrics including porous organicdielectrics, ULK (ultra-low-k) dielectrics, etc. The PMD layer 130 maybe formed using known deposition techniques, such as, for example, ALD(atomic layer deposition), CVD (chemical vapor deposition), PECVD(plasma enhanced CVD), spin on deposition, or PVD (physical vapordeposition), followed by a planarization process which is performedusing, e.g., chemical mechanical polishing (CMP), resulting in thesemiconductor structure shown in FIGS. 3A/3B/3C.

A next process module in the fabrication process comprises a RMG processflow to replace the dummy gate structures 170 with metallic fuseelements for the vertical fuse devices in the first device region R1 andmetal gate electrodes for the FINFET devices in the second device regionR2. An exemplary RMG process module begins with removing the dummy gatestructures 170. For example, FIGS. 4A/4B/4C are cross-sectional views ofthe semiconductor structure of FIGS. 3A/3B/3C after removing the dummygate structures 170 of the vertical fuse devices and FINFET devices toform recessed regions 170-1 between the insulating sidewall spacers 140.FIG. 4B is a schematic cross-sectional view of the semiconductorstructure of FIG. 4A taken along line 4B-4B in FIG. 4A, and FIG. 4C is aschematic cross-sectional view of the semiconductor structure of FIG. 4Ataken along line 4C-4C in FIG. 4A.

The dummy gate structures 170 can be removed using known methods to formthe recesses 170-1 shown in FIGS. 4A/4B/4C. For example, the dummy polygate layer 174 can be removed using a selective dry etching or wetetching process with suitable etch chemistries, including ammoniumhydroxide (NH₄OH) or tetramethylammonium hydroxide (TMAH). The etchingof the dummy poly gate layer 174 is selective to theinsulating/dielectric materials of the PMD layer 130, the insulatingsidewall spacers 140, and the dummy gate oxide layer 172. During thepoly gate etch process, the dummy gate oxide layer 172 protects thevertical semiconductor fins 120 and 122 from being etched, as the polyetch process is highly selective to the oxide material of the dummy gateoxide layer 172. After the polysilicon material is removed, an oxideetch process is performed to etch away the dummy gate oxide layers 172selective to the material of the vertical semiconductor fins 120 and122. In this manner, the dummy gate structures 170 can be etched awaywithout damaging the vertical semiconductor fins 120 and 122.

Next, FIGS. 5A/5B/5C are cross-sectional views of the semiconductorstructure of FIGS. 4A/4B/4C after depositing a conformal layer of gatedielectric material 152A and depositing a conformal protective cappinglayer 180 over the conformal layer of gate dielectric material 152A.FIG. 5B is a schematic cross-sectional view of the semiconductorstructure of FIG. 5A taken along line 5B-5B in FIG. 5A, and FIG. 5C is aschematic cross-sectional view of the semiconductor structure of FIG. 5Ataken along line 5C-5C in FIG. 5A. As shown in FIGS. 5A/5B/5C, theconformal layer of gate dielectric material 152A is deposited to linethe exposed surfaces in the recessed 170-1 in both device regions R1 andR2. The conformal layer of gate dielectric material 152A is subsequentlyremoved from the vertical fuse device region R1, while utilized in theFINFET device region R2 to form the gate dielectric layer 152 of themetal gate electrode 150 of the FINFET device T1.

In one embodiment, the conformal layer of gate dielectric material 152Ais formed by depositing one or more conformal layers of gate dielectricmaterial over the surface of the semiconductor structure. The type ofdielectric material(s) used to form the conformal layer of gatedielectric material 152A will vary depending on the application. Forexample, the conformal layer of gate dielectric material 152A maycomprise, e.g., nitride, oxynitride, or oxide or a high-k dielectricmaterial having a dielectric constant of about 3.9 or greater. Forexample, the conformal gate dielectric material 152A can include ahigh-k dielectric material, including, but not limited to, SiO₂ (k−3.9),HfO₂ (k=25), HfSiO₄ (k=11), ZrO₂ (k=25), Al₂O₃ (k=9), TiO₂ (k=80), Ta₂O₅(k=22), La₂O₃ (k=30), SrTiO₃ (k=2000), LaAlO₃ (k=30) and combinationsthereof. In one embodiment of the invention, the conformal layer of gatedielectric material 152A is formed with a thickness in a range of about0.5 nm to about 2.5 nm, which will vary depending on the targetapplication. The conformal layer of gate dielectric material 152A isdeposited using known methods such as ALD, or CVD, for example.

The conformal protective capping layer 180 is a temporary layer that isformed over the conformal layer of gate dielectric material 152A toprotect the conformal layer of gate dielectric material 152A fromsubsequent etching steps which, as explained in further detail below,are utilized to remove the portion of the conformal layer of gatedielectric material 152A from the vertical fuse device region R1. In oneembodiment of the invention, the conformal protective capping layer 180is formed of a material, or combination of materials, which is etchresistance to the etch processes used to remove the portion of theconformal layer of gate dielectric material 152A from the vertical fusedevice region R1, while having etch selectivity with regard to theconformal layer of gate dielectric material 152A so that the protectivecapping layer 180 can be subsequently removed without damaging theunderlying conformal layer of gate dielectric material 152A. Forexample, in one embodiment, the protective capping layer may be formedof TiN.

Next, FIGS. 6A/6B/6C are cross-sectional views of the semiconductorstructure of FIGS. 5A/5B/5C after removing portions of the conformallayer of gate dielectric material 152A and the protective capping layer180 in the vertical fuse device region R1. FIG. 6B is a schematiccross-sectional view of the semiconductor structure of FIG. 6A takenalong line 6B-6B in FIG. 6A, and FIG. 6C is a schematic cross-sectionalview of the semiconductor structure of FIG. 6A taken along line 6C-6C inFIG. 6A. In one embodiment, the portions of the conformal layer of gatedielectric material 152A and the protective capping layer 180 in thevertical fuse device region R1 can be removed using standardphotolithographic techniques.

For example, a layer of photoresist material can be deposited on top ofsemiconductor structure shown in FIGS. 5A/5B/5C and thenlithographically patterned (exposed and developed) to form a photoresistmask having an opening that exposes the stack of layers 152A/180 in thevertical fuse device region R1. One or more sequential etch processesare then performed to etch away the exposed portions of the protectivecapping layer 180 and the conformal layer of gate dielectric material152A in the vertical fuse device region R1. The etching can be performedusing a dry etch process such as RIE (reactive ion etching) or otheretch processes with etching chemistries that are suitable to etch thematerial (e.g., TiN) of the protective capping layer 180 and theunderlying layer of gate dielectric material 152A (e.g., HfO₂).

Following the etch process, the photoresist mask is stripped using knownetch techniques and etch chemistries (e.g., plasma ashing), resulting inthe semiconductor structure shown in FIGS. 6A/6B/6C. After strippingaway the photoresist mask, another etch process is then performed toetch away the remaining portion of the protective capping layer 180 inthe device region R2. The protective capping layer 180 is etchedselective to the materials of the gate dielectric layer 152A, the PMDlayer 130, the insulating sidewall spacers 140, and the portions of thevertical semiconductor fin 120 exposed in the recesses 170-1 in thevertical fuse device region R1, etc.

FIGS. 7A/7B/7C are cross-sectional views of the semiconductor structureshown in FIGS. 6A/6B/6C after removing the protective capping layer 180in the FINFET device region R2 and depositing a conformal layer of workfunction metal 154A over the surface of the semiconductor structure inthe device regions R1 and R2. FIG. 7B is a schematic cross-sectionalview of the semiconductor structure of FIG. 7A taken along line 7B-7B inFIG. 7A, and FIG. 7C is a schematic cross-sectional view of thesemiconductor structure of FIG. 7A taken along line 7C-7C in FIG. 7A. Asshown in FIGS. 7A/7B/7C, the conformal layer of work function metal 154Ais deposited to line the exposed surfaces in the recesses 170-1 in bothdevice regions R1 and R2.

As depicted in FIGS. 7A and 7C, the portion of the verticalsemiconductor fin 122 exposed in the recess 170-1 in the device regionR2 is covered with the conformal gate dielectric and work function metallayers 152A and 154A, which forms the high-k metal gate stack structure152/154 of the metal gate electrode 150 of the FINFET device T1, asshown in FIG. 1A. In addition, as shown in FIGS. 7A and 7B, the portionsof the vertical semiconductor fin 120 that are exposed in the recesses170-1 in the device region R1 are covered with the conformal layer ofwork function metal 154A. The conformal layer of work function metal154A in the recesses 170-1 of the device region R1 serves multiplepurposes.

For example, as discussed above with reference to FIG. 2, the conformallayer of work function metal 154A comprises a thin interface layer whichprovides a mechanism to program a given vertical fuse device by meltingor vaporizing some or substantially all of the work function metalmaterial (which is disposed on the upper and sidewalls surfaces of thevertical semiconductor fin 120) when a programming voltage VP is appliedto the metal fuse element 160 of the given vertical fuse device. Themelting/vaporizing is achieved as a result of a high heat density thatoccurs when high density current flows in the high resistance interfacebetween the work function metal layer and the vertical semiconductor fin120. Moreover, the conformal layer of work function metal 154A in thedevice region R1 serves as a wetting layer or seed layer whengrowing/reflowing/depositing the metallic material that forms the metalelectrode layers 156 of the metallic fuse elements 160.

The conformal layer of work function metal 154A may be formed of one ormore types of metallic materials, including, but not limited to, TiN,TaN, TiAlC, Zr, W, Hf, Ti, Al, Ru, Pa, TiAl, ZrAl, WAl, TaAl, HfAl,TiAlC, TaC, TiC, TaMgC, or other work functions metals or alloys thatare commonly used to obtain target work functions that a suitable forthe type of FINFET devices (e.g., n-type or p-type) that are to beformed in the given device regions. The conformal layer of work functionmetal 154A is deposited using known methods such as ALD, CVD, etc. Inone embodiment, the conformal layer of work function metal 154A isformed with a thickness in a range of about 2 nm to about 5 nm.

To provide context as to dimensions of the vertical fuse devices F1/F2and FINFET device T1 as shown in FIG. 7A, in one embodiment of theinvention, a distance L1 (in the X direction) between the inner surfacesof the insulating sidewall spacers 140 is in a range of about 10 nm toabout 20 nm, while the distance L2 within the recesses 170-1 (in deviceregion R1) between the insulating sidewall spacers 140 with theconformal layer of work function metal 154A disposed on the sidewallsurfaces of the spacers 140 is less than about 10 nm. The distance L1represents a gate length of the FINFET devices (e.g., device T1) in thedevice region R2.

A next process module in the RMG process flow comprises etching away theoverburden materials of the conformal gate dielectric and work functionmetal layers 152A and 154A, and recessing the conformal gate dielectricand work function metal layers 152A and 154A to a target depth withinthe recesses 170-1. As an initial step, FIGS. 8A/8B/8C arecross-sectional views of the semiconductor structure of FIGS. 7A/7B/7Cafter depositing an organic planarization layer 185 to fill the recesses170-1 between the insulating sidewall spacers 140 with organicplanarizing material. FIG. 8B is a schematic cross-sectional view of thesemiconductor structure of FIG. 8A taken along line 8B-8B in FIG. 8A,and FIG. 8C is a schematic cross-sectional view of the semiconductorstructure of FIG. 8A taken along line 8C-8C in FIG. 8A. The organicplanarization layer 185 utilized for etch-back processing of theconformal gate dielectric and work function metal layers 152A and 154A.The organic planarization layer 185 can be formed using known organicmaterials and deposition techniques (e.g., spin on deposition).

Next, FIGS. 9A/9B/9C are cross-sectional views of the semiconductorstructure of FIGS. 8A/8B/8C after etching the organic planarizing layer185 down to a target level within the recesses 170-1 between theinsulating sidewall spacers 140. FIG. 9B is a schematic cross-sectionalview of the semiconductor structure of FIG. 9A taken along line 9B-9B inFIG. 9A, and FIG. 9C is a schematic cross-sectional view of thesemiconductor structure of FIG. 9A taken along line 9C-9C in FIG. 9A.The organic planarization layer 185 can be etched using a dry etchprocess with an etch chemistry that is suitable to each the organicmaterial of the organic planarization layer 185. As shown in FIGS.9A/9B/9C, the recessing of the organic planarization layer 185 isperformed to expose portions of the conformal gate dielectric and workfunction metal layers 152A and 154A on the upper surface of theinsulating layer 130, and on the upper inner sidewall surfaces of theinsulating sidewall spacers 140 within the recesses 170-1. The exposedportions of the conformal gate dielectric and work function metal layers152A and 154A as shown in FIGS. 9A/9B/9C are then etched away to formthe semiconductor structure shown in FIGS. 10A/10B/10C.

In particular, FIGS. 10A/10B/10C are cross-sectional views of thesemiconductor structure of FIGS. 9A/9B/9C after etching away the exposedportions of conformal gate dielectric and work function metal layers152A and 154A in the device regions R1 and R2. FIG. 10B is a schematiccross-sectional view of the semiconductor structure of FIG. 10A takenalong line 10B-10B in FIG. 10A, and FIG. 10C is a schematiccross-sectional view of the semiconductor structure of FIG. 10A takenalong line 10C-10C in FIG. 10A. As shown in FIGS. 10A and 10B, theportions of the conformal work function metal layer 154A which arecovered by the remaining organic material of the organic planarizationlayer 185 within the recesses 170-1 in the device region R1 form theindividual work function metal layers 154 of the metallic fuse elements160 of the vertical fuse devices F1 and F2 in the device region R1.

In addition, as shown in FIGS. 10A and 10C, the portions of theconformal gate dielectric and work function metal layers 152A and 154Awhich are covered by the remaining organic material of the organicplanarization layer 185 within the recess 170-1 in the device region R2form the high-k metal gate stack structure 152/154 of the metal gateelectrode 150 of the FINFET device T1 in the device region R2. Theexposed portions of the conformal gate dielectric and work functionmetal layers 152A and 154A in the device regions R1 and R2 can be etchedselective to the materials of PMD layer 130 and the insulating sidewallspacers 140 using known etching techniques and suitable etchchemistries.

A next step in the exemplary process flow is to form the metal electrodelayers 156 within the recesses 170-1 in the device regions R1 and R2 tocomplete the formation of the metallic fuse elements 160 of the verticalfuse devices F1 and F2 in the device region R1, and to completeformation of the metal gate electrode 150 of the FINFET device T1 in thedevice region R2. For example, FIGS. 11A/11B/11C are cross-sectionalviews of the semiconductor structure of FIGS. 10A/10B/10C afterstripping away remaining portions of the organic planarizing layer 185and depositing a layer of metallic material 156A to fill the recesses170-1 between the insulating sidewall spacers 140 with metallicmaterial. FIG. 11B is a schematic cross-sectional view of thesemiconductor structure of FIG. 11A taken along line 11B-11B in FIG.11A, and FIG. 11C is a schematic cross-sectional view of thesemiconductor structure of FIG. 11A taken along line 11C-11C in FIG.11A. As shown in FIGS. 11A and 11B, the recesses 170-1 in the deviceregion R1 are completely filled the metallic material 156A, and as shownin FIGS. 11A and 11C, the recess 170-1 in the device region R2 iscompletely filled with the metallic material 156A.

In one embodiment of the invention, the layer of metallic material 156Acomprises a low-resistance conductive material including, but notlimited to, W, Al, Ni, Co, or any metallic or conductive material thatis commonly used to form gate electrode structures. In otherembodiments, the layer of metallic material 156A may comprises a metalsilicide such as Ni silicide or Co silicide. The layer of metallicmaterial 156A can be formed by depositing a metallic material such asaluminum, and then performing a metal reflow process to allow the layerof metallic material to reflow into and fill the recess 170-1. Inanother embodiment, the layer a metallic material 156A may be a metallicmaterial such as tungsten which is deposited using CVD, for example.

Following deposition of the layer of metallic material 156A, aplanarization process (e.g., CMP) may be performed to remove theoverburden metallic material on the upper surface of the semiconductorstructure by planarizing the surface down to the PMD layer 130.Following the planarization process, an etch back process is performedto recess the layer of metallic material 156A within the recesses 170-1in the device regions R1 and R2. For example, FIGS. 12A/12B/12C arecross-sectional views of the semiconductor structure of FIGS.11A/11B/11C after etching the layer of metallic material 156A down to atarget level within the recesses 170-1 between the insulating sidewallspacers 140 to form the separate metal electrode layers 156 of themetallic fuse elements 160 of the vertical fuse devices F1 and F2 in thedevice region R1, and to form the metal gate electrode 150 of the FINFETdevice T1 in the device region R2. FIG. 12B is a schematiccross-sectional view of the semiconductor structure of FIG. 12A takenalong line 12B-12B in FIG. 12A, and FIG. 12C is a schematiccross-sectional view of the semiconductor structure of FIG. 12A takenalong line 12C-12C in FIG. 12A.

As shown in FIGS. 12A and 12B, the layer of metallic material 156A isetched down within the recesses 170-1 of the vertical fuse device regionR1 to a level of the upper portion of the conformal work function metallayer 154 on the sidewall surfaces of the insulating sidewall spacers140. As shown in FIGS. 12A and 12C, the layer of metallic material 156Ais etched down within the recesses 170-1 of the FINFET device region R2to a level of the upper portion of the conformal gate dielectric andwork function metal layers 152 and 154 on the sidewall surfaces of theinsulating sidewall spacers 140. The layer of metallic material 156A canbe recessed using suitable etch process with etch chemistries that aresuitable to etch the metallic material 156A.

A next step in the fabrication process comprises forming the cappinglayers 145 within the recesses 170-1 to cover the metallic fuse elements160 of the vertical fuse devices F1/F2 in the device region R1, and tocover the metal gate electrode 150 of the FINFET device T1 in the deviceregions R2. For example, FIGS. 13A/13B/13C are cross-sectional views ofthe semiconductor structure of FIGS. 12A/12B/12C after forming thedielectric capping layers 145 to cover the metallic fuse elements 160 ofthe vertical fuse devices F1/F2, and to cover the metal gate electrode150 of the FINFET device T1. FIG. 13B is a schematic cross-sectionalview of the semiconductor structure of FIG. 13A taken along line 13B-13Bin FIG. 13A, and FIG. 13C is a schematic cross-sectional view of thesemiconductor structure of FIG. 13A taken along line 13C-13C in FIG.13A.

The dielectric capping layers 145 can be formed by depositing a layer ofdielectric material, such as SiN, to fill the upper portions of therecesses 170-1 with dielectric material, followed by a CMP process toremove the overburden dielectric material and planarize the surface ofthe semiconductor structure down to the upper surface of the PMD layer130, resulting in the semiconductor structure shown in FIGS.13A/13B/13C. Following formation of the dielectric capping layers 145,the process flow continues with forming the vertical contacts 200, 202,210 and 212, as shown in FIGS. 1A/1B/1C, using known methods asdiscussed above.

It is to be understood that the methods discussed herein for fabricatingvertical fuse devices and FINFET device can be incorporated withinsemiconductor processing flows for fabricating other types ofsemiconductor devices and integrated circuits with various analog anddigital circuitry or mixed-signal circuitry. In particular, integratedcircuit dies can be fabricated with various devices such as field-effecttransistors, bipolar transistors, metal-oxide-semiconductor transistors,diodes, capacitors, inductors, etc. An integrated circuit in accordancewith the present invention can be employed in applications, hardware,and/or electronic systems. Suitable hardware and systems forimplementing the invention may include, but are not limited to, personalcomputers, communication networks, electronic commerce systems, portablecommunications devices (e.g., cell phones), solid-state media storagedevices, functional circuitry, etc. Systems and hardware incorporatingsuch integrated circuits are considered part of the embodimentsdescribed herein. Given the teachings of the invention provided herein,one of ordinary skill in the art will be able to contemplate otherimplementations and applications of the techniques of the invention.

Although exemplary embodiments have been described herein with referenceto the accompanying figures, it is to be understood that the inventionis not limited to those precise embodiments, and that various otherchanges and modifications may be made therein by one skilled in the artwithout departing from the scope of the appended claims.

What is claimed is:
 1. A semiconductor device, comprising: a pluralityof vertical semiconductor fins formed on a semiconductor substrate, theplurality of vertical semiconductor fins comprising a first verticalsemiconductor fin and a second vertical semiconductor fin; a verticalfuse device comprising a metallic fuse element formed over a portion ofthe first vertical semiconductor fin, wherein the metallic fuse elementcomprises a first conformal metallic layer formed on the portion of thefirst vertical semiconductor fin, and a first metallic electrode layerformed on the first conformal metallic layer; and a FINFET (Fin FieldEffect Transistor) device comprising a metallic gate electrode formedover a portion of the second vertical semiconductor fin, wherein themetallic gate electrode comprises a high-k metallic gate stack structureconformally formed on the portion of the second vertical semiconductorfin and a second metallic electrode layer formed on the high-k metallicgate stack structure, wherein the high-k metallic gate stack structurecomprises a conformal layer of dielectric material formed on the portionof the second vertical semiconductor fin and a second conformal metalliclayer formed on the conformal layer of dielectric material; wherein thefirst conformal metallic layer and the second conformal metallic layerare patterned from a same conformal layer of metallic material; andwherein the first metallic electrode layer and the second metallicelectrode layer are patterned from a same layer of metallic material. 2.The device of claim 1, wherein the metallic fuse element of the verticalfuse device and the metallic gate electrode of the FINFET device areconcurrently formed as part of a RMG (replacement metal gate) process.3. The device of claim 1, further comprising: a first fuse contactformed in contact with the metallic fuse element of the vertical fusedevice; and a second fuse contact formed in contact with a portion ofthe first vertical semiconductor fin adjacent to the vertical fusedevice.
 4. The device of claim 1, wherein the metallic fuse element isformed between insulating sidewall spacers of the vertical fuse device,and wherein the metallic gate electrode is formed between insulatingsidewall spacers of the FINFET device.
 5. The device of claim 1, whereinthe conformal layer of metallic material that is patterned to form thefirst conformal metallic layer and the second conformal metallic layercomprises a work function metallic material that is utilized to obtain atarget work function for the high-k metallic gate stack structure of themetallic gate electrode of the FINFET device.
 6. The device of claim 1,wherein the conformal layer of metallic material that is patterned toform the first conformal metallic layer and the second conformalmetallic layer comprises at least one of TaN, TiN, and TiAlC.
 7. Thedevice of claim 1, wherein the conformal layer of dielectric materialcomprises a high-k dielectric material having a dielectric constant k ofabout 3.0 or greater.
 8. The device of claim 1, wherein the layer ofmetallic material that is patterned to form the first metallic electrodelayer and the second metallic electrode layer comprises at least one ofAl, W, Co and a metal silicide.
 9. The device of claim 1, furthercomprising a first capping layer formed on the metallic fuse element ofthe vertical fuse device and a second capping layer formed on themetallic gate electrode of the FINFET device.
 10. The device of claim 9,further comprising: a first vertical contact formed through the firstcapping layer in contact with the metallic fuse element of the verticalfuse device; and a second vertical contact formed through the secondcapping layer in contact with the metallic gate electrode of the FINFETdevice.
 11. A semiconductor device, comprising: a plurality of verticalsemiconductor fins formed on a semiconductor substrate, the plurality ofvertical semiconductor fins comprising a first vertical semiconductorfin and a second vertical semiconductor fin; a vertical fuse devicecomprising: a metallic fuse element formed over a portion of the firstvertical semiconductor fin, wherein the metallic fuse element comprisesa first conformal metallic layer formed on the portion of the firstvertical semiconductor fin, and a first metallic electrode layer formedon the first conformal metallic layer; a first insulating sidewallspacer surrounding the metallic fuse element; and a first capping layerformed on an upper surface of the metallic fuse element; and a FINFET(Fin Field Effect Transistor) device comprising: a metallic gateelectrode formed over a portion of the second vertical semiconductorfin, wherein the metallic gate electrode comprises a high-k metallicgate stack structure conformally formed on the portion of the secondvertical semiconductor fin and a second metallic electrode layer formedon the high-k metallic gate stack structure, wherein the high-k metallicgate stack structure comprises a conformal layer of dielectric materialformed on the portion of the second vertical semiconductor fin and asecond conformal metallic layer formed on the conformal layer ofdielectric material; a second insulating sidewall spacer surrounding themetallic gate electrode; and a second capping layer formed on an uppersurface of the metallic fuse element; wherein the first conformalmetallic layer and the second conformal metallic layer are patternedfrom a same conformal layer of metallic material; and wherein the firstmetallic electrode layer and the second metallic electrode layer arepatterned from a same layer of metallic material.
 12. The device ofclaim 11, wherein the metallic fuse element of the vertical fuse deviceand the metallic gate electrode of the FINFET device are concurrentlyformed as part of a RMG (replacement metal gate) process.
 13. The deviceof claim 11, further comprising: a first fuse contact formed in contactwith the metallic fuse element of the vertical fuse device; and a secondfuse contact formed in contact with a portion of the first verticalsemiconductor fin adjacent to the vertical fuse device.
 14. The deviceof claim 11, wherein the conformal layer of metallic material that ispatterned to form the first conformal metallic layer and the secondconformal metallic layer comprises a work function metallic materialthat is utilized to obtain a target work function for the high-kmetallic gate stack structure of the metallic gate electrode of theFINFET device.
 15. The device of claim 11, wherein the conformal layerof metallic material that is patterned to form the first conformalmetallic layer and the second conformal metallic layer comprises atleast one of TaN, TiN, and TiAlC.
 16. The device of claim 11, whereinthe conformal layer of dielectric material comprises a high-k dielectricmaterial having a dielectric constant k of about 3.0 or greater.
 17. Thedevice of claim 11, wherein the layer of metallic material that ispatterned to form the first metallic electrode layer and the secondmetallic electrode layer comprises at least one of Al, W, Co and a metalsilicide.
 18. The device of claim 11, further comprising: a firstvertical contact formed through the first capping layer in contact withthe metallic fuse element of the vertical fuse device; and a secondvertical contact formed through the second capping layer in contact withthe metallic gate electrode of the FINFET device.
 19. The device ofclaim 11, further comprising: a second metallic fuse element formed overa second portion of the first vertical semiconductor fin, wherein secondthe metallic fuse element comprises: a third conformal metallic layerformed on the portion of the first vertical semiconductor fin, and athird metallic electrode layer formed on the second conformal metalliclayer; a third insulating sidewall spacer surrounding the secondmetallic fuse element; and a third capping layer formed on an uppersurface of the second metallic fuse element.
 20. The device of claim 19,further comprising a fuse contact formed in contact with a portion ofthe first vertical semiconductor fin disposed between the first andsecond metallic fuse elements.